1. Field of the Invention
The present invention relates to tape heaters for heating or keeping warm a straight or curved pipe provided in a precision apparatus or device, capable of being wound around the pipe, and particularly to a tape heater intended for use in a clean room which hardly generates dust.
2. Description of the Related Art
For heating or keeping warm straight or curved pipes in a precision apparatus or device, for example, Japanese Unexamined Patent Application Publication No. 11-108283 has disclosed a pipe having a heater in contact along the internal surface of the pipe. For example, Japanese Unexamined Patent Application Publication No. 2002-295783 has disclosed a mantle heater having a shape corresponding to the shape of an object, namely, a straight or curved pipe, comprising an internal layer and an external layer formed of a flexible synthetic resin sheet and a heating element between the internal and external layers. Furthermore, for example, Japanese Unexamined Patent Application Publication No. 2002-228087 has disclosed a heat-insulating fiberglass tape comprising a fiberglass tape and thin thermoplastic sheets bonded on the upper and lower surfaces of the fiberglass tape by heat adhesion.
For use of the pipe with a heater of Japanese Unexamined Patent Application Publication No. 11-108283, it is necessary to select a pipe suitable for the shape of portions to be heated. For a special shape, a pipe with such a shape has to be additionally designed. Mass production is therefore difficult. Furthermore, the pipe with a heater is difficult to apply to a pipe with a small diameter.
In the mantle heater of Japanese Unexamined Patent Application Publication No. 2002-295783, whose mantle is made of a flexible synthetic resin, it is necessary to select a mantle according to the inner diameter of the pipe to be heated.
The heat-insulating fiberglass tape of Japanese Unexamined Patent Application Publication No. 2002-228087 is applicable to various shapes of pipes and heat-resistant because it comprises thin thermoplastic resin sheets bonded by heat adhesion to the upper and lower surfaces of a fiberglass tape capable of being wound. In addition, it has been designed to minimize glass fibers flying off. However, the fiberglass tape is merely for insulating heat, but not for heating to maintain a predetermined temperature.